polish air force checkerboard
The national aircraft marking of the Polish Air Force, equivalent to roundels. Adopted on 1 December 1918, it consists of four equal squares, of which the upper left and lower right are white, and the other two – red. These are surrounded by a border of inverted (counterchanged) colours 1/5 the thickness of a single square. In 1993 the colours were reversed (i.e. white in the upper left).